TWM607373U - Stepless speed regulation control circuit of single-phase AC motor - Google Patents

Abstract

A single-phase AC motor stepless speed regulation control circuit, including four rectifier diodes, three field effect transistors, a current detection resistor, an AC positive half-cycle synchronous signal circuit, an AC negative half-cycle synchronous signal circuit, and a modulation pulse Speed control signal circuit; wherein the negative poles of the first and second rectifier diodes are electrically connected to the two output terminals of the AC power supply, the positive poles of the first and second rectifier diodes are both grounded, and the third and fourth rectifier diodes are connected to the ground. The positive pole of the pole body is electrically connected to the two output terminals of the AC power supply, and the negative poles of the third and fourth rectifier diodes are respectively electrically connected to the drains of the first and second field effect transistors. The first and second field effect transistors are electrically connected to each other. The source electrode of the FET is electrically connected to the drain electrode of the third FET. The source terminal of the third FET is connected to a current detection resistor and then grounded; both ends of a single-phase AC motor are connected to the drain of the first and second FETs. Between the poles, the AC negative half cycle synchronization signal circuit is electrically connected to the grid of the first field effect transistor, the AC positive half cycle synchronization signal circuit is electrically connected to the grid of the second field effect transistor, and the modulation pulse speed control signal circuit is electrically connected to the third field. The grid of the effect tube is electrically connected. The single-phase AC motor stepless speed control module provided by this creation has a simple circuit structure, no EMI/EMC problems, easy processing, low cost, no heat generation, small size, and efficiency High advantages.

Description

Single-phase AC motor stepless speed regulation control circuit

This creation relates to an AC motor speed regulation control circuit, in particular to a single-phase AC motor stepless speed regulation control circuit.

At present, single-phase AC motors on the market consist of a main coil L1, a secondary coil L2, and a starting capacitor C to form a basic circuit structure, commonly known as an AC induction motor or a squirrel cage motor. Single-phase AC motors are often used in small household appliances such as electric fans, water-cooled fans, and air cleaners. As the most commonly used power drive motors for general small household appliances, they have the advantages of long life, high torque, and low cost. The stepless speed regulation control of single-phase AC motors has always been the goal of engineers' efforts.

At present, the speed regulation methods of single-phase AC motors on the market and their corresponding advantages and disadvantages are mainly reflected as follows:

The first one is to use the coil tapping method to perform three-stage speed regulation. The main circuit principle is shown in Figure 1. It uses the increase in the number of coil turns in the AC motor, and the connector is connected to the mechanical switch. The impedance increased by the increase in the number of coil turns is used. There are limited three-speed gears. The advantage of this speed regulation method is that it does not require an electronic control board, and the cost is low. The main disadvantages are: ①It can only do a limited three-stage or four-stage speed change, and cannot achieve stepless speed regulation; ②Because the speed adjustment method is used to increase the coil impedance, the coil loss is large, which is easy to produce motor heating and efficiency. Poor disadvantage.

The second type, the stepless speed regulation of the phase control method, the main circuit principle and single-phase AC The waveform diagram of the motor is shown in Figure 2. Using the detection of the zero bit signal of the AC power supply, the single-chip microcomputer sends out the drive signal with the zero bit detection, and then uses the bidirectional thyristor to cut the power phase to achieve Stepless speed regulation of single-phase AC motors. The advantage of this speed regulation method is that it can achieve stepless speed regulation, and the cost of the electronic control board is lower. The main disadvantages are: ① The AC motor is prone to produce electromagnetic cutting sound when running at low speed, and it is noisy; ② Because the phase of the input power is changed to obtain the change of the average current, and then the motor speed is changed, it is difficult for the product to pass EMC/EMI. Safety certification.

The third type is the stepless speed regulation of the cycle number control method. The main circuit principle is shown in Figure 3. It uses the detection of the zero bit signal of the AC power supply, and then sends the drive signal with the zero bit detection through the single-chip microcomputer. In a certain period of time, through the number of positive and negative half cycles, the bidirectional thyristor is switched on and off to achieve stepless speed regulation of the AC motor. The advantage of this speed regulation method is that it can achieve stepless speed regulation, and the cost of the electronic control board is lower. The main disadvantages are: ① The AC motor runs under the cycle number on and off, and the motor is prone to vibration and noise; ② Because the motor speed is changed by the number of positive and negative half cycles within a fixed time, it is easy to cause the motor fan blades to be unbalanced. .

The fourth is the stepless speed regulation method of the H bridge. The main circuit principle is shown in Figure 4. This method is the traditional method of first rectifying the AC power through the DB1 rectifier bridge for full-wave rectification, and then rectifying the AC power through the high-voltage capacitor C1 The motor is supplied with direct current or pulsating direct current, and then the zero position signal of the AC power supply is detected by the zero position detection and sent to the single-chip microcomputer. The single-chip microcomputer sends out the drive misalignment signals PWM1 and PWM2 with the zero position detection, symmetrically composed of four The H bridge composed of field effect transistors Q1-Q4 performs fast and dislocation switching, and the width of the modulated pulses PWM1 and PWM2 is controlled to realize stepless speed regulation of the AC motor. The advantage of this speed regulation method is that it can achieve high-precision stepless speed regulation. The main disadvantages are: ① After the AC is converted into pure DC or pulsating DC, then it is controlled by the single-chip The upper and lower arm drives formed by the control output and the H bridge are again converted into sine wave or square wave output, which is easy to cause conversion loss and poor power utilization efficiency; ②Because of the need to use high-voltage capacitors C1 and four field effect transistors Q1-Q4 , Two high-voltage bootstrap circuits and four MOS tube drive circuits, the circuit structure is complicated, and the cost is extremely high; ③The high-voltage capacitor C1 is needed in the circuit structure, and the high-voltage capacitor C1 has a larger volume, and the volume of the overall circuit structure also varies. Larger; ④The AC power is converted to pure DC or pulsating DC and then converted to sine wave-like or sine wave output. Here, the modulation pulses PWM1 and PWM2 need to be output symmetrically. The software control program is complicated, which will easily cause the motor to commutate. The dead zone will burn the MOS tube; ⑤Because of the DC or pulsating DC power supply, its output waveform is a six-step square wave or a sine-like wave, and the motor is noisy.

The purpose of this creation is to provide a single-phase AC motor stepless speed regulation control circuit, which can achieve high-precision stepless speed regulation, at the same time the circuit structure is simpler, and the cost is lower. Circuit.

To achieve the above purpose, the single-phase AC motor stepless speed regulation control circuit provided by this creation includes a first rectifier diode, a second rectifier diode, a third rectifier diode, and a fourth rectifier diode. The first field effect tube, the second field effect tube, the third field effect tube, the current detection resistor and the AC positive half cycle synchronous signal circuit, the AC negative half cycle synchronous signal circuit and the modulation pulse speed control signal circuit; among them the first rectifier diode The negative pole of is electrically connected to the second output terminal of the AC power source, the negative pole of the second rectifier diode is electrically connected to the first output terminal of the AC power source, and the positive poles of the first rectifier diode and the second rectifier diode are both grounded, The positive pole of the third rectifier diode is electrically connected to the first output terminal of the AC power source, the positive pole of the fourth rectifier diode is electrically connected to the second output terminal of the AC power source, and the negative pole of the third rectifier diode is electrically connected to the first field. The drain of the effect tube is electrically connected, the negative electrode of the fourth rectifier diode is electrically connected to the drain of the second field effect tube, and the source of the first field effect tube is electrically connected to the second field effect tube. The source of the tube should be electrically connected to the drain of the third FET, the source of the third FET is connected to the current detection resistor and then grounded; the two ends of the single-phase AC motor are connected to the drain of the first FET and the second Between the drains of the field effect tube, the AC negative half cycle synchronization signal circuit is electrically connected to the grid of the first field effect tube, and the AC positive half cycle synchronization signal circuit is electrically connected to the grid of the second field effect tube to modulate the pulse speed control signal The circuit is electrically connected with the grid of the third field effect transistor.

The single-phase AC motor stepless speed regulation control module provided by this creation has the advantages of high safety, easy processing, cost saving, easy maintenance, reduced volume, and high efficiency due to the simple circuit structure and no EMI/EMC problems. .

AC1: The first output terminal

AC2: second output

D1: The first rectifier diode

D2: The second rectifier diode

D3: The third rectifier diode

D4: The fourth rectifier diode

Q1: The first field effect tube

Q2: The second field effect tube

Q3: The third field effect tube

RS: current sense resistor

M: Single-phase AC motor

10: AC negative half cycle synchronization signal circuit

20: AC positive half cycle synchronization signal circuit

30: Modulation pulse speed control signal circuit

200: MCU

201: Input

Figure 1 is a circuit diagram of the three-stage speed regulation of an AC motor by means of a coil tapping method in the prior art.

The second figure is the circuit principle diagram of the phase control method in the prior art to realize the stepless speed regulation of the AC motor and the waveform diagram of the AC motor.

Figure 3 is a circuit diagram of the stepless speed regulation of an AC motor by the cycle number control method in the prior art and a waveform diagram of the AC motor.

Figure 4 is the circuit principle diagram of the stepless speed regulation method of the AC motor implemented by the H-bridge in the prior art and the waveform diagram of the AC motor.

Figure 5 is a schematic circuit diagram of the main structure of the single-phase AC motor stepless speed regulation control circuit in the creative embodiment.

Figure 6 is a diagram of the working current direction of the single-phase AC motor stepless speed regulation control circuit in the AC negative half cycle in the creative embodiment.

Figure 7 is a diagram of the working current direction of the single-phase AC motor stepless speed regulation control circuit in the AC positive half cycle in the creative embodiment.

Figure 8 is a schematic diagram of waveforms at various points of the single-phase AC motor stepless speed regulation control circuit in the creative embodiment.

Figure 9 is a circuit diagram of the positive half-cycle discharge circuit of the back electromotive force of the single-phase AC motor stepless speed regulation control circuit in the creative embodiment.

Figure 10 is the negative half-cycle discharge circuit diagram of the motor back electromotive force of the single-phase AC motor stepless speed regulation control circuit in the creative embodiment.

Figure 11 is the AC positive and negative half-cycle synchronization signal and modulated pulse speed control signal of the single-phase AC motor stepless speed regulation control circuit in the creative embodiment, as well as the load waveform diagram of the single-phase AC motor.

Figure 12 is a specific application circuit diagram of the single-phase AC motor stepless speed regulation control circuit in the creative embodiment.

Figure 13 is the circuit schematic diagram of Figure 12 and the waveform diagram of the AC motor.

The creation will be further described in detail below in conjunction with the embodiments of the drawings.

This creation first provides a single-phase AC motor stepless speed regulation control circuit. Please refer to Figure 5. Its main structure includes a first rectifier diode D1, a second rectifier diode D2, and a third rectifier diode. Body D3, a fourth rectifier diode D4, a first field effect tube Q1, a second field effect tube Q2, a third field effect tube Q3, a current detection resistor RS, an AC negative half cycle synchronization signal circuit 10, An AC positive half-cycle synchronous signal circuit 20 and a modulated pulse speed control signal circuit 30; wherein the negative electrode of the first rectifier diode D1 is electrically connected to the second output terminal AC2 of the AC power source, and the negative electrode of the second rectifier diode D2 is electrically connected to the second output terminal AC2 of the AC power supply. The first output terminal AC1 of the AC power supply is electrically connected, and the first rectifier diode D1 and The positive poles of the second rectifying diode D2 are all grounded, the positive pole of the third rectifying diode D3 is electrically connected to the first output terminal AC1 of the AC power supply, and the positive pole of the fourth rectifying diode D4 is connected to the second output terminal of the AC power supply. AC2 is electrically connected, the negative pole of the third rectifying diode D3 is electrically connected to the drain of the first field effect transistor Q1, the negative pole of the fourth rectifying diode D4 is electrically connected to the drain of the second field effect transistor Q2, and the first The source of the FET Q1 and the source of the second FET Q2 are electrically connected to the drain of the third FET Q3, and the source of the third FET Q3 is connected to the current detection resistor RS and then grounded; a single-phase AC The two ends of the motor M are connected between the drain of the first field effect transistor Q1 and the drain of the second field effect transistor Q2. The AC negative half cycle synchronization signal circuit 10 is electrically connected to the grid of the first field effect transistor Q1. The positive half-cycle synchronization signal circuit 20 is electrically connected to the gate of the second field effect transistor Q2, and the modulation pulse speed control signal circuit 30 is electrically connected to the gate of the third field effect transistor Q3.

Please refer to Figure 6, during the positive half-duty cycle of the AC power supply, the operating current is sent from the first output terminal AC1 of the AC power supply, passes through the third rectifier diode D3, and then passes through the single-phase AC motor M through the second field effect The tube Q2, after passing through the third field effect tube Q3 and the current detection resistor RS, flows back to the second output terminal AC2 of the AC power supply through the first rectifier diode D1 to form a current loop. At this time, both ends of the single-phase AC motor M Will get an AC positive half-cycle working current waveform; please refer to Figure 7, in the negative half-cycle of the AC power supply, the working current is sent from the second output terminal AC2 of the AC power supply, and then passes through the fourth rectifier diode D4. The single-phase AC motor M flows back to the first output terminal AC1 of the AC power supply through the second rectifier diode D2 through the first field effect transistor Q1, the third field effect transistor Q3 and the current detection resistor RS, forming a The current loop, at this time, the two ends of the single-phase AC motor M will get a negative half-cycle working current waveform, so, through the above action, the two ends of the single-phase AC motor M will get a sine wave voltage, each point waveform Refer to Figure 8 for details, and by adjusting the pulse width of the modulating pulse speed control signal circuit 30, the grounding signal can be adjusted accordingly. For the average current in the positive and negative half-waves of the phase AC, please refer to Figures 9 to 11. This creation also uses the pulse speed control signal in the low-level time t, that is, when the third FET Q3 is OFF, the single The back electromotive force generated by the positive and negative half-wave operation of the phase AC motor M performs a self-discharge loop to protect the first field effect tube Q1 and the second field effect tube Q2, thereby realizing stepless speed control of the single-phase AC motor M.

The pulse speed control signal in the modulated pulse speed control signal circuit 30 can be provided by any external device. Please refer to Figures 12 and 13. In this embodiment, the modulated pulse speed control signal control circuit 30 also includes a circuit for generating The single-chip microcomputer 200 that modulates the pulse speed control signal is connected to the input terminal 201 of the linear speed control button for controlling the speed of the single-phase AC motor M. The single-chip microcomputer 200 generates a corresponding modulation pulse according to the input signal of the speed control button The speed control signal circuit 30 has a pulse width speed control signal. In addition, the modulated pulse speed control signal circuit 30 also includes a power bridge rectifier circuit, a step-down circuit, and an optocoupler isolation circuit. The input ends are respectively electrically connected to the two output ends of the AC power supply. The output end of the power bridge rectifier circuit is connected to the input end of the step-down circuit, and the output end of the step-down circuit is electrically connected to the single-chip microcomputer 200 to supply power to the single-chip 200 and the output of the single-chip 200 The modulated pulse speed control signal is first connected to the optocoupler isolation circuit, and then is electrically connected to the gate of the third field effect transistor Q3 after passing through the push-pull driving circuit of the third field effect transistor Q3.

The AC negative half cycle synchronization signal circuit 10 further includes an AC negative half cycle detection circuit and a negative half cycle synchronous drive circuit. The AC negative half cycle detection circuit is electrically connected to the AC second output terminal AC2, and the other end is connected to the negative half cycle synchronization. The negative half-cycle synchronous driving circuit is electrically connected to the gate of the first field effect transistor Q1, and the AC positive half-cycle synchronous signal circuit 20 further includes an AC positive half-cycle detection circuit and a positive half-cycle synchronous drive circuit. The AC positive half-cycle detection circuit is electrically connected to the AC first output terminal AC1, and the other end is connected to the positive half-cycle synchronous drive circuit. The positive half-cycle synchronous drive circuit is then electrically connected to the gate of the second field effect transistor Q2. The AC negative Half a week The detection circuit and the AC positive half cycle detection circuit respectively take out the AC negative half cycle synchronization signal and the AC positive half cycle synchronization signal through two high impedance resistors, and they are used to drive the first field effect transistor Q1 and the second field effect transistor Q2 respectively. Synchronize with AC power frequency switch function, and take out DC voltage for internal circuit use at the same time.

Compared with the prior art, the single-phase AC motor stepless speed regulation control circuit of this creation has the following advantages:

① Only four rectifier diodes and three field effect transistors, as well as an AC positive half-cycle synchronous signal circuit, an AC negative half-cycle synchronous signal circuit and a modulated pulse speed control signal circuit form the main structure of the circuit, which has a small size and no The advantages of EMI/EMC interference, no heat generation, low cost and high efficiency.

②Using the positive and negative half waves of the AC power supply to directly power the AC motor alternately through the third rectifier diode and the fourth rectifier diode, and at the same time replace the first MOS tube and the second MOS tube in the upper arm of the H bridge. There are two sets of high-voltage bootstrap circuits and two sets of MOS tube drive circuits.

③The first rectifier diode and the second rectifier diode are responsible for forming the common ground effect of the entire control circuit; the third rectifier diode and the fourth rectifier diode can automatically commutate according to the power frequency, which simplifies the control of the microcontroller software Program.

④ The third rectifier diode and the fourth rectifier diode can not only change phases automatically, because they are directly powered by AC, but also solve the problem of conversion efficiency.

⑤At the same time, the back electromotive force generated by the positive and negative half-wave operation of the AC motor is used for the self-discharge loop to protect the first field effect tube and the second field effect tube within the pulse low level time.

⑥Because of the direct AC power supply, it also solves the problem of motor noise.

To sum up, this creation actually has its excellent advanced practicality among similar products. At the same time, we have checked the domestic and foreign technical data about this type of structure, and the same structure has not been found in the literature. Therefore, This creation actually has the requirements for a new patent, and Yan has filed an application in accordance with the law.

However, the above are only the preferred and feasible embodiments of this creation, so any equivalent structural changes made by applying this creation specification and the scope of patent application should be included in the patent scope of this creation.

AC1: The first output terminal

AC2: second output

D1: The first rectifier diode

D2: The second rectifier diode

D3: The third rectifier diode

D4: The fourth rectifier diode

Q1: The first field effect tube

Q2: The second field effect tube

Q3: The third field effect tube

RS: current sense resistor

M: Single-phase AC motor

10: AC negative half cycle synchronization signal circuit

20: AC positive half cycle synchronization signal circuit

30: Modulation pulse speed control signal circuit

Claims (6)

A single-phase AC motor stepless speed regulation control circuit, which contains: A first rectifier diode, a second rectifier diode, a third rectifier diode, a fourth rectifier diode, a first field effect tube, a second field effect tube, a third field Effect tube, a current detection resistor, an AC positive half-cycle synchronous signal circuit, an AC negative half-cycle synchronous signal circuit, and a modulated pulse speed control signal circuit; wherein, the negative electrode of the first rectifier diode and the second output terminal of the AC power supply Electrically connected, the negative pole of the second rectifier diode is electrically connected to the first output end of the AC power supply, the positive poles of the first rectifier diode and the second rectifier diode are both grounded, and the positive pole of the third rectifier diode is connected to the AC The first output terminal of the power supply is electrically connected, the positive pole of the fourth rectifier diode is electrically connected with the second output terminal of the AC power supply, the negative pole of the third rectifier diode is electrically connected with the drain of the first field effect transistor, and the fourth rectifier diode is electrically connected to the drain of the first field effect transistor. The negative electrode of the rectifier diode is electrically connected to the drain of the second field effect tube, the source of the first field effect tube and the source of the second field effect tube are electrically connected to the drain of the third field effect tube, and the third field effect tube is electrically connected to the drain of the third field effect tube. The tube source terminal is connected to the current detection resistor and then grounded; the two ends of a single-phase AC motor are connected between the drain of the first field effect tube and the drain of the second field effect tube, and the AC negative half-cycle synchronous signal circuit is connected to the first field. The grid of the effect tube is electrically connected, the AC positive half-cycle synchronization signal circuit is electrically connected with the grid of the second field effect tube, and the modulation pulse speed control signal circuit is electrically connected with the grid of the third field effect tube; During the positive half-duty cycle of the AC power supply, the working current is sent from the second output terminal of the AC power supply, passes through the fourth rectifier diode and then through the single-phase AC motor, through the second field effect tube, and then through the current detection resistor. The first rectifier diode flows back to the first output terminal of the AC power supply to form a current loop. At this time, the two ends of the single-phase AC motor will get a positive half-cycle AC working current waveform; during the negative half-cycle of the AC power supply, work The current is sent from the first output terminal of the AC power source, passes through the third rectifier diode, and then through the single-phase AC motor, through the first field effect tube, and then through The current detection resistor flows back to the second output end of the AC power supply through the second rectifier diode to form a current loop. At this time, the two ends of the single-phase AC motor will get an AC negative half-cycle working current waveform; by adjusting the modulation pulse adjustment The pulse width of the speed signal can adjust the average current in the positive and negative half-wave of the in-phase AC to the ground. At the same time, the back electromotive force generated by the positive and negative half-wave operation of the single-phase AC motor during the pulse low level is used to carry out the self-discharge circuit. The first field effect tube and the second field effect tube are protected, thereby realizing stepless speed control of the single-phase AC motor. According to the single-phase AC motor stepless speed control circuit described in item 1 of the scope of patent application, it also includes a single-chip microcomputer that can generate the pulse speed control signal in the modulated pulse speed control signal circuit. According to the single-phase AC motor stepless speed regulation control circuit described in item 2 of the scope of patent application, the single-phase AC motor is connected to the input terminal of the linear speed regulation button for controlling the speed of the single-phase AC motor. The signal generates a speed control signal corresponding to the pulse width of the modulation pulse speed control signal circuit. According to the single-phase AC motor stepless speed regulation control circuit described in item 2 of the scope of patent application, the modulated pulse speed regulation signal circuit further includes a power bridge rectifier circuit, a step-down circuit and an optocoupler isolation circuit, The two input ends of the power bridge rectifier circuit are electrically connected to the two output ends of the AC power supply, the output end of the power bridge rectification circuit is connected to the input end of the step-down circuit, and the output end of the step-down circuit is electrically connected to the single-chip microcomputer. For power supply, the modulated pulse speed control signal output by the single-chip microcomputer is first connected to the optocoupler isolation circuit, and then electrically connected to the grid of the third field effect tube through the driving circuit of the third field effect tube. According to the single-phase AC motor stepless speed regulation control circuit described in item 1 of the scope of patent application, the AC negative half-cycle synchronous signal circuit further includes an AC negative half-cycle detection circuit and a negative half-cycle synchronous drive circuit. The half-cycle detection circuit is electrically connected to the AC second output terminal, and the other end is connected to the negative half-cycle synchronous drive circuit, which is then connected to the first FET. The grid is electrically connected, and the AC positive half-cycle synchronous signal circuit further includes an AC positive half-cycle detection circuit and a positive half-cycle synchronous drive circuit, the AC positive half-cycle detection circuit is electrically connected to the AC first output terminal, and the other end is connected The positive half-cycle synchronous drive circuit, the positive half-cycle synchronous drive circuit is electrically connected to the gate of the second field effect transistor, the AC negative half-cycle detection circuit and the AC positive half-cycle detection circuit take out the AC negative half-cycle synchronous signal and the AC positive The half-cycle synchronization signal is used to drive the first field effect tube and the second field effect tube, respectively, to perform the switching function in synchronization with the AC power frequency. According to the single-phase AC motor stepless speed regulation control circuit according to the 5th item of the scope of patent application, the AC negative half-cycle synchronous signal circuit and the AC positive half-cycle synchronous signal circuit are respectively composed of an AC second output terminal and an AC first output At the end, the AC negative half-cycle synchronization signal and the AC positive half-cycle synchronization signal are respectively taken out through at least one high-impedance resistor to drive the first field effect tube and the second field effect tube respectively to perform the switching function in synchronization with the AC power frequency.

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